Load development distance

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!Peter!
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Joined: Sun Oct 30, 2016 6:35 am

Load development distance

#1 Postby !Peter! » Tue Oct 17, 2017 10:07 pm

Hi All,
I've seen it recommended by williada that load development should be done at least 140yds.

However, I've got access to a 100yd indoor range rated for 50BMG so I'm wondering what I'd lose by going to a shorter distance but have completely controlled environment.

Would appreciate anyone's thoughts on this.

Thanks
!Peter!

Gyro
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Location: New Zealand

Re: Load development distance

#2 Postby Gyro » Wed Oct 18, 2017 3:49 am

Great question Peter. I'd be most keen to hear some answers to this one. Without the obfuscation that often accompanies this subject.

johnk
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Location: Brisbane

Re: Load development distance

#3 Postby johnk » Wed Oct 18, 2017 7:54 am

According to BR shooters, indoor ranges aren't necessarily a completely controlled environment. For example, turbulence from the shots becomes a form of wind/mirage. For example, shots fired adjacent to walls have their flight influenced by them.

jasmay
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Joined: Fri Sep 28, 2012 9:26 pm

Re: Load development distance

#4 Postby jasmay » Wed Oct 18, 2017 8:26 am

I think you will find the main belief behind the 140yd is that the projectile doesn't "go to sleep" as people say (stop its pitching and yawing) and settle down until a bit after 100yds.

Norm
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Location: Gippsland, Victoria

Re: Load development distance

#5 Postby Norm » Wed Oct 18, 2017 9:25 am

If I had a 100 yard indoor range I would use the heck out of it..........

Brad Y
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Re: Load development distance

#6 Postby Brad Y » Wed Oct 18, 2017 6:31 pm

Yes the idea of 140yds I believe was to allow projectile to go to sleep but also be close enough to not allow conditions to affect it as much. It depends what you have access to. Plenty of loads have been developed at 100yds but knowing what to look for to take further back is key. I have done a lot of work with williadas methods and found them to work but I've gone back to tuning at 800 or 900m for my long range barrels. Just harder to work around the weather to do it. First time I used a williada tune on my short range barrel at 600yds I scored a 60.10, he knows his stuff

DenisA
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Re: Load development distance

#7 Postby DenisA » Wed Oct 18, 2017 10:04 pm

jasmay wrote:I think you will find the main belief behind the 140yd is that the projectile doesn't "go to sleep" as people say (stop its pitching and yawing) and settle down until a bit after 100yds.


This is the main reason as I have heard many times.

Personally, I've done all of my development at 100y and when I'm in a node with a good load, the result is quite obvious and always under 0.3moa and regularly much tighter. So far that's with .223Rem, .308W, .284W, .300WSM and an array of different weight G7 bullets. I don't understand how they can not be going to sleep if the groups are that small?
Last edited by DenisA on Wed Oct 18, 2017 10:05 pm, edited 1 time in total.

Pommy Chris
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Re: Load development distance

#8 Postby Pommy Chris » Wed Oct 18, 2017 10:05 pm

I generally test 215's at 100 yards then if it is windy 300 if not 300. To be honest if it is a one hole group at 100 it is always good further out too. I dont buy this bullet settling down thing. I have done a load a 100 and shot a Queens and drilled the x at 1000.
Chris

jasmay
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Re: Load development distance

#9 Postby jasmay » Thu Oct 19, 2017 6:37 am

Brad Y wrote: but I've gone back to tuning at 800 or 900m for my long range barrels.


This is mainly what I do, I think it is hard to beat tuning at the range you will be shooting at.

Quick
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Location: Yanchep, Western Australia
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Re: Load development distance

#10 Postby Quick » Thu Oct 19, 2017 7:50 am

I tune at 500m and back. MV work up and then seating depth test. Has worked for my 308 and 7mm08AI.
Shaun aka 'Quick'
Yanchep, Western Australia

308 Win F/TR & F-S
7mm F-Open Shooter.

terryx
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Joined: Tue Aug 29, 2017 11:13 am

Re: Load development distance

#11 Postby terryx » Thu Oct 19, 2017 8:12 pm

](*,) 50BMG Rated where is that at. :shock:

GSells
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Re: Load development distance

#12 Postby GSells » Sat Oct 21, 2017 9:59 pm

I’ll throw my 2 c worth in !
I load test at 100 yds , then test at 600 yds . If ok then try at 800-900 yds .
Even groups shapes at 25 m’s can be helpful for the raw development first up .
There is a specific group shape to look for @ 100yds. In that the group is more vertical ragged hole than horizontal. With the slower shots going high and faster shots going low .

The 140 yds is for g 7 bullets to go to sleep. You group would theoretically be smaller at that distance than @ 100 yds .

https://youtu.be/4pF8W5liSRc
Last edited by GSells on Tue Oct 24, 2017 8:23 pm, edited 1 time in total.

johnk
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Re: Load development distance

#13 Postby johnk » Sun Oct 22, 2017 7:34 am

I used to like the way Bert Bowden ladder tested. Three rounds of each load boxed 1,2,3,4,5,6,7,1,2,3,4,5,6,7,1,2,3,4,5,6,7 at a quiet 800 yards with somebody else spotting & plotting the shots.

He would replot them by load & only then think about assessing the outcome. Worked for him, albeit TR.

!Peter!
Posts: 39
Joined: Sun Oct 30, 2016 6:35 am

Re: Load development distance

#14 Postby !Peter! » Mon Oct 23, 2017 1:54 pm

Thanks to all for your responses, and sorry for throwing a question out and not responding earlier.

johnk wrote:According to BR shooters, indoor ranges aren't necessarily a completely controlled environment. For example, turbulence from the shots becomes a form of wind/mirage. For example, shots fired adjacent to walls have their flight influenced by them.


I've seen/ heard some of these issues before and is something I'll look for at this particular range.

jasmay wrote:I think you will find the main belief behind the 140yd is that the projectile doesn't "go to sleep" as people say (stop its pitching and yawing) and settle down until a bit after 100yds.

Brad Y wrote:Yes the idea of 140yds I believe was to allow projectile to go to sleep but also be close enough to not allow conditions to affect it as much. It depends what you have access to. Plenty of loads have been developed at 100yds but knowing what to look for to take further back is key. I have done a lot of work with williadas methods and found them to work but I've gone back to tuning at 800 or 900m for my long range barrels. Just harder to work around the weather to do it. First time I used a williada tune on my short range barrel at 600yds I scored a 60.10, he knows his stuff


From the writings of williada that is my understanding as well. I had plans of following williadas' methods at 200m to compare the results with my current development methods but circumstances put a stop to that. On the upside though I now have access a 100yd indoor range :)

I'm hoping to do testing at short range and based on the results choose a 600yd and 1000yd load which will be verified at those distances.

terryx wrote:](*,) 50BMG Rated where is that at. :shock:

Sadly not in my shed, I'd rather a 300m tunnel anyway! And it's not in Oz :wink:

williada
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Re: Load development distance

#15 Postby williada » Mon Oct 23, 2017 2:20 pm

Peter, John is correct with what he says about indoor shooting but there is another factor at play when you generally compare indoors with outdoors and it is to do with bullet lift and linked to bullet yaw. Your tune for each condition tends to be in different places due to atmospheric conditions in each place. The Houston warehouse guy never won wood outdoors with the indoor tune as I understand it but advantage lay in comparing components. Of course distance was limited.

For others and trying to avoid going into wordy explanation, the indoor condition sometimes occurs in a nil wind/no lift condition with rear wind in particular, which is steady and collapses suddenly which was evident in last weekend's Vic Champs at Bendigo resulting in some elevation and lateral drift depending also on how individual's groups were oriented as they left the barrel in the protected ally beside the trees. By orientation, I mean whether node oscillation was 1:1 vertical/ horizontal or 1:2 (which you should diagnose from your short range testing) i.e. a round group or an ABC logo group representing nodes. Nothing to do with turbulence in the crosswind protected zone either. Ask yourself why a plane takes off into the wind?

The outdoor tune orients the bullet nose to the wind flow and influences angle of attack. The nil wind/no lift analogy of hitting an air pocket does not give the pill anything to chew on. In the extreme, ask yourself is the nil wind/ no lift condition any different to a barrel with a different twist rate required for sea level as compared to higher altitude? Identify and wait. Hard to catch a falling knife.

Different strategies were called for on different parts of the range over the two days at Bendigo. Other parts of the range were experiencing turbulence which expressed as washing machine mirage further from tree protection; and the further away again you got clear wind even though there was a rear fish tail which again depending on the left or right wind, the spin drift altered vertical for pimples and was complicated with added apparent aiming mark movements which appeared and disappeared. The rear wind over steep mounds produced pressure gradients, so for FO a projectile with greater radial torque would have been a better choice i.e. 7mm over 6mm. Tough days.

To find a base for the above strategies, I have always advocated that load development is best done with a right crosswind with a right twist barrel to minimise effects of spin drift variables in the hunt for a better place to be so I can be better placed to adjust for conditions during competition.

This sort of stuff affects group size at the micro level but at the macro level in terms of trajectory, indoor shooting will help you identify muzzle lift characteristics if I understand where Peter is going with this for compensation analysis. So does a test at twenty five yards. So load development distance depends on your goal and putting it all together with a myriad of considerations at different distances.

Its important to note, the group shape changes gradually past the over tuning point in the trajectory (which I have explained before with regard to angle of attack) and you need to evaluate that and find a node with a better axis (dependent on velocity and gyroscopic stability at the long distance and venue of competition in terms of environmental factors. In the past, I found a tuned group generally holds over successive distances at the same venue in that shots tend to follow a similar pattern whether they are good or bad; and like lungs they breathe in and out depending on the barrel's compensation profile i.e. positive, neutral or negative.

At an advanced level we can get into vibration analysis to quickly determine a likely load. Vibrations, driven, resonant, extraneous, reflected, stacked etc. determine a barrel's fundamental performance IMO. Therefore its important to determine a trade off with statistical analysis (which burns good barrels out) with what vibrations can account for the group shape in a series of groups.

The minimum practical distance to discount coning effects because we don't want to confuse them with vibration effects iwhich are magnified at long range is 140 yards, as I found doing Project Penumbra for Bert Bowden and the NRAA with statistically significant tests. Others such as Cooper, Vaughn and Litz have discussed the significance of the coning distance too. As such, it becomes the minimum practical distance to discount environmental factors such as the effects of wind and spin drift, light and mirage. At 100 yards, groups are so small at times its hard to see how the components of the group are shaping up for vibration analysis. At 140 yards, they open up sufficiently to see that. The one forty yards test sheets are A4 paper and are an efficient way of measuring results and storing them for further reference.

I had prepared diagrams of this, but Photobucket has to be paid for now as I have just discovered trying to post the links. Sorry.

Denis I have opened up my contact for a short time, so if you send me your private email, I can send you the prepared diagrams which I can not send through this system with Photobucket. Hopefully the pictures will reveal why 100 yards has its limitations and why you can form tiny groups within the coning distance if your reloads have low SD or may be compensating at that point but are not necessarily the optimum. Traditionally, 100 yards was an efficiency measure as one minute of angle subtended to approximately one inch. It wasn't performance based for boat tailed bullets designed for long range.

One swallow does not make a summer and fundamental group formation needs to be repeatable. Edited as I had typed it out quickly before.


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